The genera Phaeothamnion Lagerheim, Tetrachrysis gen. nov. and Sphaeridiothrix Pascher et Vlk (Chrysophyceae)

Culturing experiments are described in which the life cycles of several clones of Phaeothamnion borzianum, a supposedly palmelloid form of the latter, and Sphaeridiothrix compressa are investigated. The three types of algae turned out to be quite distinct taxa, not at all connected by intergrading forms as has been suggested in the literature. A new genus – to be named Tetrachrysis iis proposed to accommodate the taxon, formerly regarded as a palmelloid phase of Phaeothamnion.